Such a method is known, for example, from U.S. Pat. Nos. 4,714,117 and 5,447,201, European patent application No. 0588421 and from UK patent application No. 2,320,938.
In the methods known from these prior art references the control valve or valves are adjusted such that the production of undesired fluids, such as water and/or gas is reduced and that the inflow of fluids is equalised along the length of the inflow region of the well in a substantially static fashion.
In particular in horizontal wells there is a long horizontal inflow region where production of fluids tends to be larger near the heel of the well than near the toe of the well. As a result of such unequal inflow of fluid the risk of water and/or gas coning and ultimately of water and/or gas breakthrough is larger near the heel than near the toe of the well.
The known inflow equalisation methods indeed reduce the risk of water and/or gas coning near the heel of the well, but they significantly reduce the production rate of the well and do not adequately minimize the amounts of water and/or gas produced after water and/or gas breakthrough has occurred.
It is an object of the present invention to overcome the problems associated with the prior art systems and to provide an oil or gas production method in which the problem of water and/or gas coning and of high fluid influx from highly permeable reservoir strata is reduced with only a minimal reduction of the production rate of the well.